[18684] in cryptography@c2.net mail archive
Re: SecurID and garage door openers
daemon@ATHENA.MIT.EDU (Adam Shostack)
Tue Oct 18 13:18:15 2005
X-Original-To: cryptography@metzdowd.com
X-Original-To: cryptography@metzdowd.com
Date: Tue, 18 Oct 2005 12:23:18 -0400
From: Adam Shostack <adam@homeport.org>
To: "Travis H." <solinym@gmail.com>
Cc: cryptography@metzdowd.com
In-Reply-To: <d4f1333a0510180125v2b2ad2d5h759e037979794c54@mail.gmail.com>
On Tue, Oct 18, 2005 at 03:25:40AM -0500, Travis H. wrote:
| Speaking of two-factor authentication, can anyone explain how servers
| validate the code from a SecurID token in the presence of clockskew?
| Does it look backwards and forwards in time a few minutes?
Yes, it rolls forward and back 3-5 cycles. The server maintains a
list of what time it thinks the token thinks it is. So its not
testing what time it is, its testing what time the token thinks it is.
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